nring_asphalt_road

Procedural Nordschleife asphalt for the road ribbon: worn grey aggregate with a fine stone grain and micro-normal, the famous patchwork of newer repair sections with tar sealing seams, darker polished tyre tracks, and crisp white edge lines that stay antialiased at any distance. Reads lateral position from the ribbon's u (0..1 across) and distance from v (metres / v_scale). Used by the nring_road_tex material.